Of all the things that have been talked about and written about for Windows 8, none have been more discussed than its new Metro user interface and its touch screen centric design. Many have complained that it is too much of a change from previous versions of Windows. Today, in a new and massive post on the Windows 8 blog, Microsoft goes over the decisions it has made for the Windows 8 user interface.

Written by Jensen Harris, the Director of Program Management for the Windows 8 User Experience team, the blog first goes over all of the user interfaces for the previous versions of Windows, starting from from Windows 1 in 1985, which was made to be interacted with mainly by a keyboard (the PC mouse was just an option).

Windows 3.0/3.1 was next in 1990, which introduced the Program Manager and File Manager interfaces. Windows 95, launched in 1995, brought us the now familiar Start button, the taskbar, the Explorer and the desktop which remain even now in Windows 7. Windows XP, launched in 2001, brought some refinements to those features, including the Start menu.

Windows Vista, in 2007, gave use the controversial Aero "glass" art style. Finally, Windows 7 in 2009 gave us even more changes to the Start button and other aspects of the OS.

Harris said that for Windows 8, Microsoft had a number of goals in terms of supporting new features, including being able to have a PC or other Windows 8 product be connected to the Internet all the time. Having content not just on the PC itself but also stored on cloud servers was another feature goal, as was supporting the rise of PC portability. Finally, Microsoft wanted to emphasize the person that would be using a Windows 8 device, rather than the files.

The blog goes over some of the other aspects of Windows 8, much of which has been written about before. That includes giving Windows 8 devices a long battery life, the use of Live Tiles and of course the Windows 8 touch interface with the Metro UI.

Even though Windows 8 has the Metro touch interface, the regular desktop will still be around, and Harris says it is just as important to Microsoft to support such an interface for Windows 8. He states:

It is pretty straightforward. The desktop is there to run the millions of existing, powerful, familiar Windows programs that are designed for mouse and keyboard. Office. Visual Studio. Adobe Photoshop. AutoCAD. Lightroom. This software is widely-used, feature-rich, and powers the bulk of the work people do on the PC today. Bringing it forward (along with the metaphors such as manual discrete window sizing and overlapping placement) is a huge benefit when compared to tablets without these features or programs. It is an explicit design goal of Windows 8 to bring this software forward, run it better than in any previous version of Windows, and to provide the best environment possible for these products as they evolve into the future as well.

Harris said that Microsoft will be making some changes to the desktop UI for Windows 8, which will include having some of the Metro look put into the UI. However, he added that not everything will be transferred. He said:

While much of the Metro style UI uses white text on a colorful saturated background, the desktop in Windows 8 will continue to use black text on light-colored chrome, as in Windows 7. This choice was made to help preserve maximum compatibility with existing programs.

The desktop windows will still look "light and airy", according to Harris. The team also wanted it to look much like Windows 7. Harris said:

We made a conscious effort to relate the visual appearance of the Windows 8 desktop to the visual appearance of the familiar Windows 7 desktop. This helps people who want to predominantly use the desktop feel comfortable and immediately at home in the new environment.

The blog also goes over much of the other small changes that will be made to the desktop UI in Windows 8. Harris said:

We applied the principles of “clean and crisp” when updating window and taskbar chrome. Gone are the glass and reflections. We squared off the edges of windows and the taskbar. We removed all the glows and gradients found on buttons within the chrome. We made the appearance of windows crisper by removing unnecessary shadows and transparency. The default window chrome is white, creating an airy and premium look. The taskbar continues to blend into the desktop wallpaper, but appears less complicated overall.

To complete the story, we updated the appearance of most common controls, such as buttons, check boxes, sliders, and the Ribbon. We squared off the rounded edges, cleaned away gradients, and flattened the control backgrounds to align with our chrome changes. We also tweaked the colors to make them feel more modern and neutral.

Harris added that some of these changes to the desktop will be seen in the upcoming Release Preview version of Windows 8, which is scheduled to launch in the first week of June. However, the rest of the changes to the desktop UI won't be seen until the final version of Windows 8 is launched later in 2012.

Harris ends the blog by saying that he and the team know that the large changes in the Metro user interface for Windows 8 have generated a lot of debate, some for and some against. He added:

The full picture of the Windows 8 experience will only emerge when new hardware from our partners becomes available, and when the Store opens up for all developers to start submitting their new apps. At the same time, there's no doubt that all the features of Windows 8 are compelling on today's hardware designed for Windows 7—with or without touch. Since we designed Windows 8 to work great for laptops and desktops, it will work naturally for your Windows 7 hardware. Think of past versions of Windows that worked on existing hardware but were even better with new hardware. That's our approach with Windows 8.